1. The Field of the Invention
This invention relates to processing apparatus. More precisely, this invention relates to multi-stage rotary processors particularly useful for processing plastic and polymeric materials.
2. Description of the Prior Art
Rotary processors are known to the art. Details relating to such processors are described in U.S. Pat. Nos. 4,142,805: 4,194,841, 4,207,004; 4,213,709; 4,227,816; 4,255,059; 4,289,319; 4,300,842; 4,329,065 and in commonly assigned, copending application Ser. No. 971,332 filed Dec. 20, 1978, now abandoned. All of the above patents and applications are incorporated here by reference.
Multi-stage rotary processors are also known to the art. U.S. Pat. No. 4,227,816 specifically relates to a rotary processor having two stages in three sections. Rotary processors of U.S. Pat. No. 4,227,816 comprise a rotatable element or rotor carrying a plurality of processing channels and a stationary element providing a coaxial closure surface cooperatively arranged with the channels to provide enclosed processing passages. Also associated with the stationary element are inlets, outlets and blocking members for each passage and material transfer passages or grooves formed in the closure surface of the stationary element and arranged to transfer material from a passage (or passages) of one stage to a passage (or passages) of another stage. As disclosed in U.S. Pat. No. 4,227,816, one processing stage involves two primary or supply sections. Each primary or supply section of the first stage is arranged at each end of the rotor and are separated from each other by a second processing stage adapted to receive material from each section of the first stage.
U.S. Pat. No. 4,213,709 also relates to a multi-stage rotary processor which provides two processing stages including a primary processing passage interconnected to a further processing passage. The preferred processor involves two primary processing passages, each arranged at each end of the rotor with the primary processing passages separated by two further processing passages adapted to receive material from the primary processing passages. In the processors described in U.S. Pat. Nos. 4,213,709 and 4,227,816, the passages adapted to receive material from passages of another stage are of a selected geometry relative to the geometry of the passages from which the material is received. Essentially, the geometry is selected to provide the material receiving passage with the capability to process and discharge material at a volume rate which is less than the volume rate at which material is received by the passage. Such geometries assure complete filling of the receiving passages and accordingly provide a uniform rate of discharge and uniform discharge pressure for material processed in the material receiving passage.
Serious complications however, have developed in multi-stage rotary processors having material receiving passages in which a different geometry is required for passages receiving material from a passage(s) of another stage. For example, certain polymeric processes require a passage geometry which provides the passage with the capability to process and discharge material at a volume rate greater than the rate at which material is received by the passage. This variance or mismatch between the rate at which the passage receives material and the volume/rate capability of the passage to process and discharge material can cause large pressure, flow and temperature fluctuations in processing passages and particularly at the discharge of the rotary processor.
This invention is directed to multi-stage rotary processors having a novel, improved design which provides special advantages in terms of efficiency, quality of product and overall processing performance characteristics.